The present invention relates to lift trucks, and in particular to a dual mast lift truck designed for lifting heavy unbalanced and awkward loads.
The conventional lift arrangement for fork lift trucks comprises a pair of tines which are mounted on a single mast or column. Both tines move together up and down the mast, and are designed to lift palletized loads, transport bins, racks, and other standardized containers and objects.
The movement of large, heavy industrial machines, such as presses, brakes, packaging equipment, etc., in factories and plants is a very time consuming, tedious, hazardous and difficult task. Such equipment is typically quite heavy and awkward, and does not have balanced weight distribution or handy grip holds from which the machinery can be lifted.
Heretofore, trucks with standard lift arrangements, as discussed hereinabove, have been used to move heavy industrial equipment. Most factories do not have permanent overhead cranes or other similar lift devices to move equipment. To pick up machinery with a conventional, single mast lift arrangement, blocks must be attached to the forks so that they will mate with those surfaces from which the machine is to be lifted. The blocked lift forks are then positioned underneath the machine, and raised until the blocked forks abut the machine. It is extremely difficult to accurately adjust the blocks on the forks so that they will abut the machine squarely and evenly. The machine must then be chained or strapped to the lift forks to insure that the machine will not fall off the forks during transport. When the machinery to be moved is raised to the transport position, unless the forks are positioned directly below the machine's center of gravity, the machine will tend to tip or slide off of the lift forks. As a result, the chains or strapping must be very securely attached to the machine and lift tines. The stress applied to the machine by the chains can cause damage to the machine, particularly if the load shifts slightly. The machine must often be set down, and the blocks and forks repositioned to achieve proper balance. The difficulties associated with properly balancing heavy machinery on the tines of standard, single mast lift trucks creates an inherently dangerous situation, which is quite hazardous to the safety of the workman.